This is the first release of a BBCode "parser" that translates BBCode tags like [url] or [b]. It's part of a package for my CMS lite application.

 
CREATE OR REPLACE PACKAGE cm_parse
IS
  /* parse blog entries */
  FUNCTION bbcode_to_html(
    p_text  IN CLOB
  , p_en_Id IN cm_entry.en_Id%TYPE DEFAULT NULL
  ) RETURN CLOB
  ;
END cm_parse;
/

CREATE OR REPLACE PACKAGE BODY cm_parse
IS
  /* private constants */
  ST_CODE    CONSTANT PLS_INTEGER := 1;
  ST_NOPARSE CONSTANT PLS_INTEGER := 2;

  /* private types */
  TYPE t_ref_links IS TABLE OF c_ref_links%ROWTYPE;

  TYPE t_arg IS RECORD (key     VARCHAR2(255)
                       ,key_val VARCHAR2(255)
                       );

  TYPE t_args IS TABLE OF t_arg INDEX BY BINARY_INTEGER;

  TYPE t_status IS VARRAY(2) OF BOOLEAN;

  /* private procedures */
  /* get arguments */
  PROCEDURE get_args(
    p_tag  IN  VARCHAR2
  , p_args OUT t_args
  )
  IS
    v_argc    PLS_INTEGER := 0;
    v_arg     VARCHAR2(255);
    v_key     VARCHAR2(255);
    v_key_val VARCHAR2(255);
    v_args    t_args;
  BEGIN
    LOOP
      v_argc := v_argc + 1;
      v_arg  := REGEXP_SUBSTR(p_tag, '([^] ]+)', 2, v_argc);  
     
      EXIT WHEN v_arg IS NULL;

      v_key     := LOWER(REGEXP_SUBSTR(v_arg, '([^=]+)'));
      v_key_val := SUBSTR(v_arg, LEAST(LENGTH(v_key) + 2, 250));

      v_args(v_argc).key     := v_key;
      v_args(v_argc).key_val := v_key_val;
    END LOOP;

    p_args := v_args;
  END get_args;

  /* public procedures */
  /* parse blog entries */
  FUNCTION bbcode_to_html(
    p_text  IN CLOB
  , p_en_Id IN cm_entry.en_Id%TYPE DEFAULT NULL
  ) RETURN CLOB
  IS
    v_slash     CONSTANT VARCHAR2(1) := '';
    v_bracket   CONSTANT VARCHAR2(1) := '[';
    v_LF        CONSTANT VARCHAR2(1) := CHR(13);

    v_pos       PLS_INTEGER;
    v_pos_end   PLS_INTEGER;
    v_start     PLS_INTEGER;
    v_len       PLS_INTEGER := NVL(LENGTH(p_text), 0);
    v_searched  VARCHAR2(255);
    v_replace   VARCHAR2(255);
    v_args      t_args;
    v_source    VARCHAR2(32000) := DBMS_LOB.SUBSTR(p_text, 32000);
    v_text      VARCHAR2(32000);
    v_status    t_status := t_status(FALSE, FALSE);
  BEGIN
    v_pos := 0;

    LOOP
      v_start := v_pos + 1;

      Debug('v_start: ' || v_start);

      /* don't parse text enclosed by the noparse tags */
      IF v_status(ST_NOPARSE) THEN
         v_pos   := LEAST(NVL(NULLIF(INSTR(v_source, v_slash,      v_start), 0), v_len + 1)
                         ,NVL(NULLIF(INSTR(v_source, '[/noparse]', v_start), 0), v_len + 1)
                         );
      ELSE
         v_pos   := LEAST(NVL(NULLIF(INSTR(v_source, v_slash,   v_start), 0), v_len + 1)
                         ,NVL(NULLIF(INSTR(v_source, v_LF,      v_start), 0), v_len + 1)
                         ,NVL(NULLIF(INSTR(v_source, v_bracket, v_start), 0), v_len + 1)
                         );
      END IF;

      v_text := v_text || SUBSTR(v_source, v_start, v_pos - v_start);

      EXIT WHEN NVL(v_pos, 1) > v_len;

      v_searched := SUBSTR(v_source, v_pos, 1);

      CASE v_searched
           WHEN v_slash THEN
                v_pos      := v_pos + 1;
                v_searched := SUBSTR(v_source, v_pos, 1);

                v_replace  := CASE v_searched
                                   WHEN '<' THEN '<'
                                   WHEN '>' THEN '>'
                                   WHEN '&' THEN '&'
                                   ELSE v_searched
                              END;
           WHEN v_LF THEN
                v_pos      := v_pos + 1;
               
	        IF v_status(ST_CODE) THEN
		   v_replace := v_searched;
		ELSE
		   v_replace := '<br>';
		END IF;
           WHEN v_bracket THEN
                v_pos_end := INSTR(v_source, ']', v_pos + 1) - v_pos + 1;
                
                IF v_pos_end > 0 THEN
                   v_searched := SUBSTR(v_source, v_pos, v_pos_end);

                   v_replace  := CASE v_searched
                                      WHEN '[b]'  THEN '<b>'
                                      WHEN '[i]'  THEN '<i>'
                                      WHEN '[u]'  THEN '<u>'
                                      WHEN '[p]'  THEN '<p>'
                                      WHEN '[/b]' THEN '</b>'
                                      WHEN '[/i]' THEN '</i>'
                                      WHEN '[/u]' THEN '</u>'
                                      WHEN '[/p]' THEN '</p>'
                                      WHEN '[/url]' THEN '</a>'
                                      WHEN '[/img]' THEN '>'
                                      WHEN '[/doc]' THEN '>'
                                      ELSE NULL 
                                 END;

                   CASE v_searched
                        WHEN '[code]' THEN 
			     v_replace            := '<pre>';
			     v_status(ST_CODE)    := TRUE;
		        WHEN '[/code]' THEN
			     v_replace            := '</pre>';
			     v_status(ST_CODE)    := FALSE;
                        WHEN '[noparse]' THEN 
			     v_replace            := ' ';
			     v_status(ST_NOPARSE) := TRUE;
		        WHEN '[/noparse]' THEN
			     v_replace            := ' ';
			     v_status(ST_NOPARSE) := FALSE;
			ELSE
			     NULL;
	           END CASE;

                   IF v_replace IS NULL THEN
                      get_args(p_tag => v_searched, p_args => v_args);
                      IF v_args.COUNT > 0 THEN
                         CASE WHEN v_args(1).key = 'img' THEN 
                                   v_replace := '<img srg="' || v_args(1).key_val || '>';
                              WHEN v_args(1).key = 'doc' THEN 
                                   v_replace := '<img src="f?p=999:7:0::::P7_DOC_ID:' || v_args(1).key_val || '"';
                              WHEN v_args(1).key = 'url' THEN 
                                   IF v_args(1).key_val IS NULL THEN
                                      v_args(1).key_val := REGEXP_REPLACE(REGEXP_SUBSTR(v_source
                                                                                       ,'(http://)?([^[]+)'
										       ,v_pos - v_pos_end
                                                                                       )
                                                                         ,'(http://)?(.+)'
                                                                         ,'http://2'
                                                                         );
                                   END IF;

                                   v_replace := '<a href="' || v_args(1).key_val || '">';
                              ELSE
                                   v_replace := v_searched;
                         END CASE;     
                      END IF; 
                   END IF;

                   v_pos := v_pos + v_pos_end - 1;
                ELSE
                   v_replace := '';
                END IF;
          ELSE
               RAISE_APPLICATION_ERROR(-20999, 'v_pos: ' || v_pos || ' v_searched: ' || v_searched);
      END CASE;

      v_text := v_text || v_replace;
    END LOOP;
        
    RETURN v_text || '<p>';
  END bbcode_to_html;
END cm_parse;